Thermoelectric door operating mechanism



Jam 5, 1954 v u EAL 2,665,129

THERMOELECTRIC DOOR OPERATING MECHANISM Filed Nov. 15, 1950 INVENTORS VrnQrz, Durbi' y Charles T. Bui'lbm ATTO RNEY Patented Jan. 5, 1954 THERMOELECTRIC DOOR OPERATING MECHANISM Vernon Durbin, Waban, and Charles T. Button,

Needharn, Mass, assignors to National Pneumatic 00., Inc., Boston, Mass., a corporation of Delaware Application November 13, 1950, Serial No. 195,332

1. Claim. 1

This invention relates to door operating mechanism, and particularly to the opening and. closing of doors by power; the application of the power being under the control of electrical connections responsive automatically to changes in the rate of heat transfer at a control point in the vicinity of the dOOr or doors to be operated.

In places where rooms adjoin and communication there-between is by way of doors, also in the case of garage doors and doors in factories, stores warehouses, etc., it is often desirable to have the door open automatically when a person or object approaches and to close immediately after the person or object has passed through the doorway. An arrangement of this sort is particularly useful for operation of doors which connect a dining room to the kitchen of a restaurant or hotel and which are continually being opened by persons whose hands may not be free to push the door.

Electrical control devices, as heretofore known, have commonly required the erection of stanchions (as in photoelectric systems), or metallic guide-rails (as in electrostatic capacitance systems), which stanchions or guide-rails would operate to set off the initiating impulse, for operation of the doors only after entry of a person (or vehicle) into the space directly between said stanchions or guide-rails. The system herein disclosed diners from these prior systems in that the operation is initiated by the mere approach of a person (or vehicle) from any angle or direction, and without the need 0! erecting either stanchion, guide-rails, or other auxiliary mechanism in the approach path.

An object of the invention, therefore, is to provide a system of control of door operation wherein the mere approach of a person, or object, sets off an electrical initiating impulse; the impulse emanating from a single control element mounted unobtrusively in a wall or ceiling of the building, out of the actual path of approach, but within the range of energy radiated by the approaching person, or object.

A second object of the invention is to provide, in-a system of the character indicated, a control element whose electrical characteristics vary sharply in response to a. relatively slight change in the rate of heat applied thereto.

A third object is to provide, in a system having such a control element, means for sha ply v ing the rate of application of heat to such element in response to the approach of a person, or object, and with such rapidity as to cause the operation of the door to occur well in advance of actual arrival of the person, or object, at the door-way itself.

In the drawings:

Fig. 1 is a diagrammatic illustration of the system;

Fig. 2 is a schematic showing of electrical parts and connections that are preferable to those illustrated in Fig. 1 where conditions are such to permit; and Fig. 3 shows a further modification.

The arrangement is shown as applied to door operation, but it is, of course, apparent to those skilled in the art that the system is adapted for controlling and operating any form of passagecontrolling device. There is shown in the drawing a building wall 5 in which a door 6 is mounted, alon with a vertical shaft 1 which may rotate about a fixed vertical axis. Supported over the door is a pneumatic motor 8 which is connected to the door shaft by pivotally intercon nected levers. A valve 9 is electro-magnetically actuated to direct compressed air into and out of the motor 8, in alternate stages. This man nor of operating doors and the interconnection of the parts is so very well known in so many forms that it is believed that the diagrammatic illustration is sufficient. It may also be noted at this point, as will be apparent to those skilled in the art, that although a pneumatic motor is disclosed, any other form of power device may be equally well controlled and be employed for operating the door.

It is also here noted that the electromagnetic valve 9 and its association with a pneumatic motor is very well known in the art. The terminals of the solenoid winding of the electromagnetic valve are connected to the terminals of the secondary winding of a transformer H whose primary winding is under the control of a thermionic device ID for amplifying energy supplied to the device now to be described.

Mounted in the wall 4, adjacent the door, is an energy collecting device having three major components, namely, a reflector 20, a semi-conductive resistance element 21 of the thermally sensitive or thermistor class, and a window 22- of a material, such as rock salt, through which infra-red as well as all other light rays will readily pass. The terminals of the thermistor (which may correspond in principle to the element shown at 4 in the drawings of Kock Patent No. 2,522,521) connect with points 50 and 5|, respectively, of a Wheatstone bridge whose adjacent arm is formed by a second (non-exposed) thermistor 2| a. Across the central points 5|, 53 of the bridge is a transformer 2, whose secondary winding is in the control circuit of an electronic amplifier i0 supplying a transformer I, which in turn energizes the electro-magnetic portion 9 of the door operating valve, heretofore described.

Under favorable conditions it will be found possible to obtain adequate power for operation of the electromagnetic portion of the valve independently of any auxiliary amplifying agent such as the tube In of Fig. 1. In such cases it is preferable to substitute the electrical arrange-' ment indicated in Fig. 2, wherei reference numeral 3| designates a relay contact element adapted to move into bridging relationship to a pair of associated contact elements, to deliver operating current from source 32 to the valve operating electromagnet 9, whenever the thermistor 2| (corresponding to the thermistor 2| of Fig. 1) undergoes a suiliciently rapid heat change to render the circuit of the relay winding 33 effective to energize the relay and thus close the circuit to valve magnet 9, at the point 3|. For this duty there may be employed, as the magnetic relay 33, an extremely sensitive type of relay, as for example the type known in the trade as a Sensitrol relay. Also, if desired, the radiant energy collector 22 may be placed in the direct path of heat rays rising from a heat source specially provided below the floor line of the building. Such a heat source is shown in Fig. 3 as a glow grid 36 adapted to receive energizing current from a source 31, under the control of a switch 38, which may be of the manual or automatic (thermostatic) type. A protective grating 39 (with shielded louvres) would preferably be placed over the glow element 35, with its upper surface flush with the upper surface of the floor.

The thermistor circuit, in either the Fig. 1, Fig. 2, or Fig. 3 embodiment, is of such stability that when there is no person or object in th area of approach to the door, there is no flow of operating current to th winding of the electromagnetic valve 9. However, as soon as a person or object moves toward the door the resistance of the thermistor is sharply changed, causing a potential change at transformer I2 whereby the grid of tube Iii no longer acts to block the flow of electrons to the plate and the device is set in operation. The result is that a current flows in the plate circuit of the tube, and this includes the transformer H and (indirectly) the electromagnetic valve 9. The valve 9 therefore operates to apply compressed air to the engine 8 in a manner to open the door. By the time the person has passed through the open door-way the resistance of the thermistor circuit shifts back to normal and energy flow in the tube [0 ceases. Thereupon the magnet valve returns to normal position, re-directing the supply of fluid pressure so that the engine closes the door. It may be noted here that the engine illustrated is of the differential type wherein fluid pressure is always present in the smaller cylinder and the engine is moved back and forth by supplying compressed air to and exhausting it from the larger cylinder. This type of operation is well known in the art. Obviously, any other type of engine may be employed, in which case the magnet valve may be modified as required. Alternatively, in lieu of a fluid pressure engine there may be substituted an electric motor for operating the door, in which event the valve 9 will be replaced by an electric current controller.

While Fig. 2 shows heat conducting rods 23 interconnecting the heat ray receiver 22 with the thermistor 2| it is to be understood that such rods constitute merely one of the methods of delivering the operating energy to the thermistor. Alternatively, the energy delivered to the thermistor by direct radiation can be sufiicient to produce the intended operation, particularly if the material comprising the energy collector 22 is the rock salt window illustrated in Fig. 1, through which the infra-red as well as the visible light rays may pass without impedance. With a heat receiver so constructed the energy radiations of infra-red wave lengths will be sufiicient to produce virtually instantaneous response on the part of the thermistor 2| independently of any supplementary assistance, much as the heat conducting rods 23 of Fig. 2.

B using the Wheatstone bridge arrangements of Fig. 1, with two thermistors 2| and 2 la in adjacent arms of the bridge, opposite fixed resistors R, and R2 of known values, and with only thermistor 2| exposed to the energy ray striking col-" lector 22 (the thermistor 2|a being shielded therefrom) there is produced a control circuit that is promptly responsive, self-compensating in action, and adapted to prolong the energy flow in tube Ill for the complete duration of each suc-' cessively created condition of unbalance in the. bridge itself, and to cut oil such energy flow promptly upon restoration of bridge balance.

What we claim is: In the combination of a door movably mounted in a wall, a power device operatively connected to said door for opening it, a control for said power device, and an electric circuit connected to said control for actuating the latter; the improvement which consists of a device located. in one of said door or said wall adjacent said'door and exposed to the space in the vicinity of said; door through which a person or object must passto reach said door, said device detecting and being sensitive to radiations in the infra-red range, said device including a temperature-sensitive re-' sistor the resistance of which is sensibly altered by the detection by said device of infra-red radiations emanating from a person or object entering said space in the vicinity of said door, a sec-' ond similar temperature-sensitive resistor shielded from the effects of infra-red radiation in said space in the vicinity of said door and in circuit" space in the vicinity of'said door, whereby the approach of said person or said object to door will cause said door to open.

. VERNON DURBIN.

CHARLES T." BUTTON.

(References on following page) said 5 References Cited in the file of this patent UNITED STATES PATENTS Number Re. 22,709 595,343 1,715,750 1,716,775 1,760,479 1,810,172 1,820,764 1,929,273 2,031,226 2,173,455

Name Date Russell et a1. Jan. 15, 1946 Roth Dec, 14, 1897 Gano June 4, 1929 Hayes June 11, 1929 Colman May 27, 1930 Hayes June 16, 1931 Abt Aug. 25, 1931 Crago Oct. 3, 1933 Parvin Feb. 18, 1936 Roby Sept. 19, 1939 Number 6 Name Date Clark Nov. 21, 1939 Lindsay et a1 Oct. 19, 1943 Crosthwait et a1. Apr. 11, 1944 Polye June 8, 1948 Teichmann Mar. 7, 1950 Mershon Nov. 21, 1950 Buckeridge Dec. 5, 1950 Rutherford et a1. Feb. 6, 1951 Rittner Apr. 3, 1951 Callender June 5, 1951 Nickells June 12, 1951 Deubel Oct. 30, 1951 Mershon Aug. 26, 1952 

